[Boost-users] [spirit] alpha numeric characters

Hello *, I currently use boost 1.36 to parse some input line like a->b->c-> ... I thought a, b, c can be strings containing letters or digits. Until now I thought that this defines alpha numeric characters. But when using the spirit rule: +((+alnum_p)[some_callback_func] >> str_p("->")) the some_callback_func gets as input the whole input sequence (a->b->c->...). Furthermore, it than gets called for b->c->... and than c->d->... Maybe my rule is wrong, but I can't get where. Thanks for advice, Ovanes